Remote sensing represents a significant function in the exploration of minerals. Extraction and identification of mineral occurrences in semi-arid to arid regions are some of the remote sensing confirmed uses. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images have been combined with band ratio processing technique for detecting the fluorite mineral occurrences in the area around Gabal Abu Diyab, Central Eastern Desert, Egypt.  The proposed band ratio derived from ASTER images Spectra [(b8/b6) * (b5/b3)] can be considered to represent the new Fluorite Index (FI). The USGS Spectral libraries are used to extract the new index and validated it by using the field study. According to the given new Fluorite Index (FI) combined with the field observations, two occurrences of fluorite mineralization at Gabal Homrit Waggat and Gabal Ineigi have been identified. This study provides the proposed FI as a beneficial tool for fluorite exploration that could be applicable along with Arabian Nubian Shield and similar arid and semi-arid environments.